ENHANCING THE RESILIENCE OF IDAHO’S TRANSPORTATION SYSTEM TO NATURAL HAZARDS AND CLIMATE CHANGE FINAL PROJECT REPORT by Dr. Tim G. Frazier University of Idaho And Lisa Nichols University of Idaho Sponsorship Pacific Northwest Transportation Consortium (PacTrans) for Pacific Northwest Transportation Consortium (PacTrans) USDOT University Transportation Center for Federal Region 10 University of Washington More Hall 112, Box 352700 Seattle, WA 98195-2700 In cooperation with US Department of Transportation-Research and Innovative Technology Administration (RITA)
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USDOT University Transportation Center for Federal Region 10
University of Washington
More Hall 112, Box 352700
Seattle, WA 98195-2700
In cooperation with US Department of Transportation-Research and Innovative Technology
Administration (RITA)
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Disclaimer
The contents of this report reflect the views of the authors, who are responsible for the
facts and the accuracy of the information presented herein. This document is disseminated
under the sponsorship of the U.S. Department of Transportation’s University
Transportation Centers Program, in the interest of information exchange. The Pacific
Northwest Transportation Consortium, the U.S. Government and matching sponsor
assume no liability for the contents or use thereof.
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Technical Report Documentation Page 1. Report No.
2013-S-UI-0052 2. Government Accession No.
3. Recipient’s Catalog No.
4. Title and Subtitle
Enhancing the Resilience of Idaho’s Transportation Network to Natural Hazards and Climate
Change
5. Report Date
7/31//2015
6. Performing Organization Code
KLK852, 739436
7. Author(s)
Tim Frazier and Lisa Nichols
8. Performing Organization Report No.
N15-04
9. Performing Organization Name and Address
National Institute for Advanced Transportation Technology
University of Idaho
875 Perimeter Dr. MS 0901
Moscow, ID 83844-0901
10. Work Unit No. (TRAIS)
11. Contract or Grant No.
DTRT12-UTC10
12. Sponsoring Agency Name and Address
Pacific Northwest Transportation Consortium (PACTRANS) University of Washington
More Hall 112, Box 352700 Seattle, WA 98195-2700
13. Type of Report and Period Covered
July 1 2013 to July 31 2015
14. Sponsoring Agency Code
15. Supplementary Notes
16. Abstract
This research compiled information on past landslides, including date-referencing and geo-locating events; analyzed and mapped variables contributing to slide susceptibility; demonstrated the conditions of the future climate models that may increase landslide hazards; and
designated the transportation routes most vulnerable to weather-triggered landslides. The study area was reduced to the northern and central
counties, as primary and secondary transportation routes in the remainder of Idaho rarely cross areas of high topographic relief. The slide events located in this pilot study generally occur in areas of high susceptibility based on aspect, slope, and geology. The transportation routes most at
risk given projections of climate change are in the northern-most counties of Idaho: Interstate 90 and northern sections of U.S. Highway 95.
Luckily, these areas generally have dense canopy cover, an indicator of slope stability. However, land use changes, forestry management policy changes, and the threat of large-scale wildfires could each impact slope stability. With a larger, detailed record of landslide events, predictive
models for homogenous “landslide” regions could be combined with historical and projected climate data to isolate specific sections of
highways most vulnerable to extreme weather-triggered slope failures. LiDAR could greatly reduce the time and cost of compiling a landslide inventory for Idaho.
17. Key Words
Transportation infrastructure; hazards; resilience; landslides; weather and
climate; climate change;
18. Distribution Statement No restrictions. Copies available from PACTRANS:
Wilson, R.C. 1989. “Rainstorms, pore pressures, and debris flows: a theoretical framework. In:
Landslides in a semi-arid environment.” Morton, D.M., Sadler, P.M., eds. California:
Publications of the Inland Geological Society, 2: 101-117.
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APPENDIX A. LIST OF GEOCODED HISTORICAL LANDSLIDE EVENTS FROM RECONNAISSANCE
Longitude Latitude
Elevation
(ft) County Date(s) Information Source(s) Certainty of location
-116.311207 48.694458 1958 Boundary
Saturday, March 01,
1997
Boundary Hazard Mitigation Plan
(HMP) Seen in Google Earth, map in AHMP
-116.298892 48.71291 2269 Boundary
October 19, 1998-
October 20, 1998
Boundary HMP and State AHMP
2013 Map in county plan cross-referenced to Google Earth
-116.40667 48.691074 1811 Boundary
March 31, 2011-
April 11, 2011
Damage Summary Report,
Disaster Number ID11-01 Exact coordinates given in report
-116.584258 48.329641 2808 Bonner April, 1991 Bonner HMP
Approximate Only! Cross-referenced to H2O treatment
location and Google Earth
-116.89997 48.22839 2231 Bonner
March 31, 2011-
April 11, 2011
Damage Summary Report,
Disaster Number ID11-01
Approximate coordinates obtained from cross-referencing
aerial photographs in report
-116.897045 48.231764 2309 Bonner
March 31, 2011-
April 11, 2011
Damage Summary Report,
Disaster Number ID11-01
Approximate coordinates obtained from cross-referencing
aerial photographs in report
-116.861148 48.31126 2275 Bonner
March 31, 2011-
April 11, 2011
Damage Summary Report,
Disaster Number ID11-01
Approximate coordinates obtained from cross-referencing
aerial photographs in report
-116.832147 48.368522 2384 Bonner
March 31, 2011-
April 11, 2011
Damage Summary Report,
Disaster Number ID11-01
Approximate coordinates obtained from cross-referencing
aerial photographs in report
-116.535002 47.985362 2609 Kootenai
January 30, 2000
and February 11,
2000 Kootenai HMP
Seen in Google Earth, referenced to online photographs.
Unknown which slide occurred on which date.
-116.531592 47.985067 2530 Kootenai
January 30, 2000
and February 11,
2000 Kootenai HMP Seen in Google Earth, referenced to online photographs
-115.928 47.69323 2480 Shoshone
Thursday, March
31, 2011 FEMA documents Exact coordinates given in FEMA docs
-116.713297 46.499993 1199 Nez Perce
Wednesday, January
01, 1997
Idaho Transportation
Department/Disaster Declaration
Task Force Committee Report
(via Latah County records--hard
copy document)
Approximate Only!, representing road closure at
Cottonwood Creek, not the locations of multiple mud
and rock slides beyond
-116.179053 46.391673 1102 Lewis
January 1, 1997-
January 2, 1997
Idaho Transportation
Department/Disaster Declaration
Task Force Committee Report
(via Latah County records--hard
copy document)
Approximate Only!, representing road closure at
Greer, not the locations of multiple mud and rock slides
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-116.001877 46.184463 1213 Lewis
January 1, 1997-
January 2, 1997
Idaho Transportation
Department/Disaster Declaration
Task Force Committee Report
(via Latah County records--hard
copy document)
Approximate Only!, representing road closure at
Kamiah, not the locations of multiple mud and rock slides
-116.1655 46.5321 2284 Clearwater
Monday, April 11,
2011
Documentation provided by Don
Gardner, Clearwater County
Exact coordinates given in Preliminary Damage Assessment
from Don Gardner
-116.251113 46.491013 1525 Clearwater
March 31, 2011-
April 11, 2011
Damage Summary Report,
Disaster Number ID11-01
Approximate coordinates obtained from cross-referencing
aerial photographs in report
-116.169952 46.5907 2566 Clearwater
Monday, April 11,
2011
Documentation provided by Don
Gardner, Clearwater County.
Damage Summary Report,
Disaster Number ID11-01
Exact coordinates given in Preliminary Damage Assessment
from Don Gardner (refer to start of slide and start of slide
100's feet long) and obtained from cross-referencing aerial
photographs in report
-116.070184 46.183821 1673 Idaho
December 30,1996-
January 1, 1997
Idaho Transportation
Department/Disaster Declaration
Task Force Committee Report
(via Latah County records--hard
copy document)
Approximate Only! based on mileposts given for the
road closure and cross-referenced to topography
-116.32247 45.414676 1785 Idaho
January 1, 1997-
January 4, 1997
Idaho Transportation
Department/Disaster Declaration
Task Force Committee Report
(via Latah County records--hard
copy document)
Approximate, representing road closure not the locations
of mudslides
-116.356369 45.315562 2310 Idaho
January 1, 1997-
January 4, 1997
Idaho Transportation
Department/Disaster Declaration
Task Force Committee Report
(via Latah County records--hard
copy document)
Approximate, representing road closure not the locations
of mudslides
-116.11536 44.084029 2805 Boise
December 30, 1996-
January 4, 1997
Idaho Transportation
Department/Disaster Declaration
Task Force Committee Report
(via Latah County records--hard
copy document)
Approximate Only!, representing road closure at Banks
not the locations of multiple mudslides
-116.188818 43.935172 2636 Boise
December 30, 1996-
January 4, 1997
Idaho Transportation
Department/Disaster Declaration
Task Force Committee Report
(via Latah County records--hard
copy document)
Approximate Only!, representing road closure at
Horseshoe Bend not the locations of multiple mudslides
-116.120062 44.068445 2785 Boise
Wednesday, January
01, 1997 State AHMP 2013
Exact coordinates given by Keith Nottingham, ITD. Cross-
referenced to Google Earth, coordinates give toe of slide, top of
slide unknown.
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-116.114603 44.084594 2820 Boise
Tuesday, December
31, 1996
Idaho Transportation
Department/Disaster Declaration
Task Force Committee Report
(via Latah County records--hard
copy document)
Approximate Only!, representing road closure at
Banks not the locations of multiple mudslides
-115.614711 44.08266 3835 Boise
Wednesday, January
01, 1997
Idaho Transportation
Department/Disaster Declaration
Task Force Committee Report
(via Latah County records--hard
copy document)
Approximate Only!, representing road closure at
Lowman not the locations of multiple mudslides
-114.939414 44.217398 6250 Boise
January 1, 1997-
January 5, 1997
Idaho Transportation
Department/Disaster Declaration
Task Force Committee Report
(via Latah County records--hard
copy document)
Approximate Only!, representing road closure at
Stanley not the locations of multiple mudslides
-115.604564 44.05685 4857 Boise
January 1, 1997-
January 5, 1997
Idaho Transportation
Department/Disaster Declaration
Task Force Committee Report
(via Latah County records--hard
copy document)
Approximate Only!, representing road closure 4 miles
south of Lowman not the locations of multiple mudslides
-115.982285 43.650976 3118 Boise
January 1, 1997-
January 5, 1997
Idaho Transportation
Department/Disaster Declaration
Task Force Committee Report
(via Latah County records--hard
copy document)
Approximate Only!, representing road closure at Robie
Creek intersection not the locations of multiple mudslides
-116.29432 45.125501 3808 Adams
December 31, 1996-
January 4, 1997
Idaho Transportation
Department/Disaster Declaration
Task Force Committee Report
(through Latah County records--
hard copy document)
Approximate based on "eleven miles north of
New Meadows" in report.
-116.30478 45.190218 3182 Adams
December 31, 1996-
January 4, 1997
Idaho Transportation
Department/Disaster Declaration
Task Force Committee Report
(through Latah County records--
hard copy document)
Approximate based on "seventeen miles north of
New Meadows" in report. Multiple debris flows along
10-mi stretch of road during these dates
-116.325945 45.235169 2834 Adams
December 31, 1996-
January 4, 1997
Idaho Transportation
Department/Disaster Declaration
Task Force Committee Report
(through Latah County records--
hard copy document)
Approximate based on "twenty miles north of New
Meadows" in report. Multiple debris flows along
10-mi stretch of road during these dates
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-116.377683 44.851688 3618 Adams
December 31, 1996-
January 4, 1997
Idaho Transportation
Department/Disaster Declaration
Task Force Committee Report
(through Latah County records--
hard copy document)
Close to exact, cross-referenced to ITD's milepoint logs,
http://itd.idaho.gov/highways/milepointlog/
-116.379892 44.863654 3688 Adams
December 31, 1996-
January 4, 1997
Idaho Transportation
Department/Disaster Declaration
Task Force Committee Report
(through Latah County records--
hard copy document)
Close to exact, cross-referenced to ITD's milepoint logs,
http://itd.idaho.gov/highways/milepointlog/
-116.378512 44.866715 3683 Adams
December 31, 1996-
January 4, 1997
Idaho Transportation
Department/Disaster Declaration
Task Force Committee Report
(through Latah County records--
hard copy document)
Close to exact, cross-referenced to ITD's milepoint logs,
http://itd.idaho.gov/highways/milepointlog/
-116.032956 45.904117 1912 Adams
Wednesday, January
01, 1997
Idaho Transportation
Department/Disaster Declaration
Task Force Committee Report
(through Latah County records--
hard copy document)
Location of slide itself unknown. Little detail found.
Coordinates refer to closure based on milepost given.
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APPENDIX B. INTERVIEW/SURVEY QUESTIONS AND RESPONSES
The following are the answers received via email (five) and over the phone (two). Respondents are employed across the state by the Idaho
Transportation Department, Idaho Department of Lands, or work in their county’s emergency management office. In order to help protect the
anonymity of respondents, the answers to each question have been shuffled. When necessary, answers have been shortened (indicated by brackets) to
maintain anonymity. Otherwise, answers via e-mail have been preserved, and answers over the phone reflect summarized, direct quotes, so all syntax,
emphasis, and ambiguities below are part of the true answers.
1. Where are the known landslide “problem areas” in your county/district?
“Along the roads traversing up the river valleys.”
“1. US26 Ririe to Wyoming State line. 2. SH31 Swan Valley to Victor. 3. US93 Montana Line to Challis 4. [ ] (Pocatello) has several areas scattered
throughout [ ]. I know of some but not all.”
“[ ]Our landside problems are adjacent to roads throughout the county both State HWY and County Rds. Hwy 64 from Nezperce to Kamiah is of
greatest impact and concern.”
“Hwy 99 going down the grade into Kendrick; McGary Grade in Juliaetta; Hwy 3 near Juliaetta; Cedar Ridge in Kendrick.”
“I-90 East of CdA, US-95 south of CdA (N Mica), Bonners Ferry area, SH-57 north of Priest River, US-2 WSL to Priest River.”
“East of Clarkia going back 100 miles around St. Maries, called “flood woods”, mica schist very problematic—couple hundred square miles. No
towns out there, just forest roads. Two types of landslides: deep and shallow (this area has both).”
“10-15 years ago, near Glen’s Ferry that closed the road. State Hwy 55 milepost 82.2: rock- scaling project discovered landslide 300-400 feet up
from road, moved road over 20 feet. Another in Banks area–a rain on snow event. Lower Banks condemned. Since then 2 or 3 events. In 1997, 8 out
of 10 counties were affected along Highways 21, 55, and 95. Governor’s landslide task force created. A 3-day rain pineapple express melted
everything 4800 feet and lower. [ ] North of Weiser, just south of Manns creek. Route change, didn’t affect the road but almost. Rearranged the road,
overloaded material [ ]. Old Meadows, a huge ¾ mi slide not active but mapped, no roads nearby. Between Boise and Horseshoe bend, road rebuilt in
1993. [ ] North of Banks, by first railroad bridge.”
2. Are roads and infrastructure at risk in these problem areas? If so, what specifically is at risk?
“The roads and creeks. Land-sliding into a creek with threatened and endangered fish.”
“This depends on the size of the slide.”
“No, moved the roads, not that we know of.”
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“Yes, could cause road failure disrupting transportation routes and access to and from location within the county.”
“Material in roads become a road hazard, Blocking roads”
“Yes, existing and potential for landslides.”
“1. US26 Ririe to Wyoming State line @ risk items 1 bridge and several sections of the highway. 2. SH31 Swan Valley to Victor @ risk are several
sections of the highway. 3. US93 Montana Line to Challis @ risk are a couple sections of the highway.”
3A. What is the main cause of slope failure in these areas?
“Debris flow, rain on snow like 1997, little bit of everything. Post wildfire [ ] possibly a problem, still need a heavy rain…need both.”
“Poor soils and water and roadways traversing ancient landslides are the most common reasons in my district. The second most common is poor
drainage design causing soils on embankment and natural slopes to become saturated and fail.”
“Erosion; snow melt.”
“Deep seated slope failures in both cut and fill and shallow failures in all slopes often caused by solifluciton. Natural, relatively undisturbed areas are
also a threat, primarily along SH-57 and US-95 in the Bonners Ferry area.”
“Soils becoming saturated and freeze thaw events”
“Drainage, how we control water, need to get water off the road…surface or sub surface water.”
“Most generally due to too much water, we do have a dry slice that accelerates during dry times.”
3B. In your experience with slope failures in your county/district, are these events typically associated with:
Condition Number that
answered “Yes”
Additional notes submitted:
…rain-on-snow? 6 “rain on snow and are short timed except for the fixing part of the equation.”
“springtime, dependent upon weather patterns. Happen in certain area at a certain
elevation.”
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…extreme events lasting less
than a one week?
5 “concentrated rainstorms esp. near Banks (just had one last spring, was an area burned
over)”
“some events extreme for less than a day, definitely seeing more extreme events, mostly
leading to shallow landslides.”
…a season-long pattern of higher
than normal precipitation?
5 “one near Weiser”
“when you have a long winter, snow hangs around until rain starts, long term pattern
leading to rain on snow”
…post-wildfire conditions? 3 “locally, will be doing salvage logging, without triggering more landslides, what you end
up triggering is shallow landslides.”
“Not too much as we haven’t experienced the large wildfires.”
…more than one of these
circumstances?
3 “most of these on the list”
…or something else entirely? 3 “Site disturbance, changes in natural drainage or vegetation, clear cutting, etc.”
“Another contributing factor has been poor drainage design for the highway and placing
roadways on unstable or marginally stable slopes.”
“…freeze-thaw events and heavy rain storms lasting less than one week.”
4. At what time of year do most slope failures occur in your county/district?
“Spring”
“Early to mid-Spring”
“Spring, extreme thunderstorm events especially in southern Idaho. In fall sometimes.”
“Most generally January through March but occasionally due to rain storms of huge rain fall in June or July equaling more than an inch is less than
one hour.”
“Late winter and spring”
“November to June.”
“Late winter (January rain-on-snow or rapid melt) to spring”
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5. Who (agency or contact name) is responsible for monitoring potential slope failure in the “problem areas” along roads in your
county/district?
“County road districts”
“Me.” [ITD District Geologist]
“Me.” [ITD District Geologist]
“Area folks find them, report them to [ ], then try to figure out the mechanism. [ ] has his roads, IDT has their roads. Most of [ ]’s roads are gravel”
“It is shared between Operations (Maintenance) and the geotech [ ]”
“County roads: N Latah County Hwy Dist; S Latah Hwy Dist. State roads: ITD”
“We have (5) road districts and [ ]EM Coord. [ ]”
6. Who (agency or contact name) is responsible for mitigation efforts and clean-up efforts in your county/district?
“Operations, each foreman area.”
“Whoever’s maintenance areas, whoever the local guys are, not ITD”
“County road districts”
“Idaho Transportation Department District [ ].”
“Same as above question, Road District and County Emergency Management”
“[ ] is for mostly gravel roads, just a case of rebuilding the road, design to fix it.”
“It depends on the incident for cleanup efforts. All Hazard Mitigation Plan is a county-wide effort to show vulnerable areas when improvement needs
to be worked on.”
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7. In your opinion, is the absence of a comprehensive landslide record in the State of Idaho a hindrance in mitigation efforts in your
county/district? Why/why not?
“Yes, cataloging and mapping landslides and areas with a potential of landslides would be very beneficial for the ITD planning and maintenance but
also for local agencies and developers.”
“This is an ambiguous question because you don’t define what you’re talking about and it’s not a term used in the industry. ITD has been a reactive
agency when it comes to landslides. The department does not actively have a statewide database of known landslides but relies on institutional
knowledge which is very inadequate because several have been mitigated but only a few individuals know about these. The four district geologists
know of their existence but every district does not have a geologist and as for myself It has taken years of research in old plans and field work to put
together what I know about in my district.”
“YES. It would be nice to have a way to track the landslides in the county (small/large) to better mitigate the situation, ie, minimize or eliminate.”
“Yes, We have potential landslide areas that we either are not aware of their existence or do not understand their potential for destruction. Many of
the river bottoms are The USGS soils map shows many of the river bottoms Qal, alluvial deposits, we have Qls soils, landside deposits, and many of
the river valley walls are Ywu or Ywml, a Wallace formation (middle proterozoic) We have fault lines in these areas. We probably do not have a
good understanding of the potential problems these soil types could present.”
“NO Because of the Local knowledge base that exists and that remains for decades.”
“Don’t think it would make a difference or not. If it closes the road, it is cleaned up. Pollack area north of Riggins has had several road closing
events, trying to get IGS to identify landslides there, possibilities with LiDAR. Mitigation efforts aimed at county and state highways and people.”
“Yes. We don’t have a landslide inventory. Part of it is grand scheme, landslides in Idaho are not like in western Washington. But more people are
moving to Idaho, more building. Would be great to have a comprehensive inventory, especially with LiDAR. [ ]”
8. What is/are the barrier(s) to landslide documentation in your agency? …in the State?
“No clue”
“The county does not have the trained staff nor the funding.”
“Money and staff. LiDAR becoming more prevalent, building data consortiums. With LiDAR, algorithms can pick up the roughness [of a landslide].
The Oso, Washington slide brought this to light, which was preventable. But Idaho’s not a rich state.”
“In county it has to do with time, of personnel and availability of technology of the various road districts to document what they have done.”
“No Headquarters Geotechnical Section with staff and resources to archive these landslides and any information related to location, soils, mitigation
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or instrumentation.”
“Budgets and personnel. We haven’t near enough bodies, 4 geologists for the entire state, and we have very little to no budget for this work.”
“Washington State had an unstable slopes program. If there is a problem, ITD Geologists work with managers. Along Snake River, the road was built
out one lane because can’t get a hold on the slope there).”
9. Do you anticipate landslide risk will increase in the future? Why or why not?
“I don’t anticipate the risk to increase as the causes of instability are widely varied and can sometimes be controlled. The weather plays a large part in
many of our problem areas so an increase in precipitation or long periods of precipitation increases the probability of landslides occurring.”
“Hope we are gaining ground, depends on the weather, everything is weather related.”
“Yes. Due to climate conditions.”
“Yeah, two things: more extremes in weather from climate change, more high precipitation events and more people building, just like fire.”
“That honestly depends on Mother Nature. We are trying to get proactive but with only four geologists in the districts and one geotechnical engineer
in headquarters and no central program or budget to draw from for mitigation we will mostly be reactive. I believe as existing embankments and cut
slopes age and marginal soils lose their shear strength due to increased soil moisture content then yes slides will eventually increase in frequency.
Also remember that not all mitigation is permanent so some that have been stabilized may eventually fail again due to the design life of the
mitigation and possibly lack of maintenance of mitigation features.”
“No, most the county is flatter and those areas of prone sliding are documented and remain where they are.”
“As development continues on the hillsides and as logging removes timber from the hill sides, the potential will increase.”
10. Is there any other information about landslides or landslide documentation that you would like to add?
“There are many types and forms of landslides or slope instability. It would be beneficial to document and categorize each area according to the type
and risks.”
“LiDAR is really promising. Predictive tools, shallow stability analysis. Need to map existing landslides, then try to predict where they will happen.
That would fit in for everybody, tell planners to check the inventory first.”
“Now with each district having GIS personnel and a tool to capture geospatial information about landslides then it may be possible with extra
resources to gather existing data into a central repository but the key work is resources.”
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“The more opportunities we have to become educated regarding landsides, the more we are apt to either mitigate, regulate and/or prepare.”
“Said it all at the beginning: you have to think about geologic time scale versus climate change. There’s 450 feet of gravel south of town from the
Bonneville flood, came through Utah….In McCall area, they found 4 different ages of ice. Global cooling was a concern in 1970s, now it’s global
warming. Climate warming is whacky.”
“Some kind of a layer system that could be available to counties through a GIS platform.”